Host-pathogen interaction: Enterobacter cloacae exerts different adhesion and invasion capacities against different...

Area of Science:

• Microbiology
• Infectious Diseases
• Cell Biology

Background:

• Urgent need for new antibiotics against multidrug-resistant bacteria.
• Enterobacter cloacae, a gram-negative bacterium, causes severe urinary tract and lung infections (UTIs).
• Previous studies on E. cloacae pathogenicity in UTIs were limited to bioinformatics.

Purpose of the Study:

• To investigate the in vitro interaction of E. cloacae with human cell lines.
• To monitor early host-pathogen interactions, including bacterial adhesion and invasion.
• To establish a suitable in vitro model for studying E. cloacae-host cell interactions.

Main Methods:

• Flow cytometric adhesion assay.
• Classical cell counting assay.
• Gentamicin invasion assay.
• Confocal laser scanning microscopy.
• Investigation of mutant strains (fimH, fimA, csgA).

Main Results:

• E. cloacae showed strong adhesion to bladder, kidney, and lung cells, correlating with clinical UTI and lung infection relevance.
• Minimal adhesion to skin cells (A-431) and no significant interaction with intestinal cells (Caco-2, HT-29).
• E. cloacae was internalized by all tested host cells, with highest invasion rates in bladder and kidney cells.
• fimH and fimA mutants abolished adhesion to T24 bladder cells; csgA deletion had no effect.

Conclusions:

• E. cloacae exhibits distinct adhesion and invasion patterns dependent on the target human cell type.
• These patterns correlate with the bacterium's clinical relevance in causing UTIs and lung infections.
• T24 bladder cells provide a suitable in vitro system for evaluating E. cloacae adhesion and invasion.